libec_crcs.py

import ctypes
import ctypes.util
import struct
import sys
import textwrap
import zlib

lib_name = ctypes.util.find_library('erasurecode')
if not lib_name:
    lib_name = 'liberasurecode.so.1'
libec = ctypes.CDLL(lib_name)
libec_crc_alt = getattr(libec, 'liberasurecode_crc32_alt', libec.crc32)


def crc_alt(data):
	return ctypes.c_uint(libec_crc_alt(0, ctypes.c_char_p(data), len(data))).value

for frag in sys.argv[1:]:
	with open(frag, 'rb') as fp:
		header = fp.read(80)

	print(textwrap.dedent(
		'''
		Frag:       {}
		Stored CRC: {:08x}
		zlib CRC:   {:08x}
		libec CRC:  {:08x}
		'''
	).lstrip().format(
		frag,
		struct.unpack('I', header[67:71])[0],
		zlib.crc32(header[:59]),
		crc_alt(header[:59]),
	))